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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Nationally, around half of people making urgent calls for ambulance services are not then taken to hospital. This is called the non-conveyancing rate. But this rate varies two-fold from region to region. There are differences too in what happens to patients not going to hospital. Some places discharge more patients at the scene, offer telephone advice or send to other non-emergency health services like walk-in centres.

This NIHR mixed methods study used observation and analysis of routine ambulance quality data between 2013 and 2014 to find out reasons for this variation. Some factors are to do with the patients and their needs and were beyond the control of the ambulance services.  But some differences could be explained by the different ways services recorded call outcomes and calculated indicators, especially for telephone advice.

Other important factors which partly explained differences in non-conveyance rates included availability of advanced paramedics and how they were used by trusts. Different attitudes to risks of non-conveyancing in local services also seemed important in accounting for variation in practice.

The current study provides insight into service disparity. This could help standardise ambulance services and improve urgent service provision, in line with new quality indicators. However, it did not capture outcomes for all trusts, so it remains unclear whether there were any negative outcomes from ambulance non-attendance or non-conveyance.

Why was this study needed?

Ambulance services in England responded to nearly 11 million calls in 2015-16, costing £1.78 billion.

Developing ambulance service pathways for treatment out of hospital are in line with NHS policy to redesign urgent and emergency care. This includes the NHS Five Year Forward View, the Right Care programme and commissioning guidance following the 2013 NHS England Urgent and Emergency Care review.

The rationale for updating pathways from historic conveyance as default is that the great majority of patients calling for an ambulance require urgent rather than emergency care, for example following a crisis in a chronic health condition like asthma. In many of these cases, care can be provided more efficiently away from A&E.

Unwarranted variation implies inefficient care provision. The aim of this national study was to explore why non-conveyance and re-contact rates vary between and within ambulance services.

What did this study do?

As the first stage in this multi-method study, the researchers analysed individual-level call data and published Ambulance Quality Indicators, the monthly performance indicators published by NHS England. The study did not include the small Isle of Wight service, which serves less than 1% of the England population.

Ambulance Trusts used different IT systems to document calls, and calculated indicators using their own interpretations of national guidance. They applied varying inclusion and exclusion criteria, affecting interpretation of comparative data. The 2014-15 data were collected prior to the 2015 NHS Review and subsequent change in guidance.

Following a descriptive analysis of routine data, the researchers interviewed managers, paramedics and commissioners; analysed routine data against patient and service characteristics; and observed ambulance service processes. This work took place between 2015 and 2016.

What did it find?

  • At the end of 2016, the proportion of patients who were sent an ambulance service vehicle but not taken to a hospital emergency department varied two-fold between 23 and 51% among regional ambulance trusts. The proportion of 999 calls closed with telephone advice varied between 5 and 17%. Total non-conveyance, as calculated by the researchers, varied between 40 and 68%.
  • The culture of the workforce and management were associated with rates of discharge at scene. For example, where management was risk-averse toward non-conveyance, rates were lower (odds ratio 0.78, 95% confidence interval 0.63-0.98) in contrast with services where staff were highly motivated towards non-conveyance.
  • Attendance by advanced paramedics and a positive workforce culture about their added value were associated with higher rates of discharge at scene.
  • Following the closure of a call with telephone advice, the re-contact rate varied five-fold. Rates were lower than 5% in London, the East Midlands and the North West. While rates were between 10 and 15% for the West Midlands, North East and South West. Descriptive analysis showed that trusts with a high rate of non-conveyance did not necessarily have a high rate of re-contacts.

What does current guidance say on this issue?

A 2017 National Audit Office report on NHS ambulance services recommended that NHS England, NHS Improvement and ambulance services should together identify an optimal rate for the new care models. They also stated that NHS England and NHS Digital should consider more closely defining indicators, such as resolution of calls over the phone, to improve comparisons.

Following the Ambulance Response Programme, NHS England introduced a new series of indicators and measures in May 2018. This is part of a wider policy drive to improve the urgent and emergency care system.

What are the implications?

We don’t yet know enough about how to reduce unwarranted variation in conveyance rates. This detailed national descriptive study increases what we know about variation in ambulance services. This knowledge may help standardise services, and further improve ways people can receive urgent and emergency services closer to home. It is a relatively recent shift in the role of ambulance staff from mainly transporting patients needing emergency care to hospital, to managing many patients at home.

This study shows that parts of the country may be taking steps to do this more effectively than others. There are benefits for patients and the wider system when people can be kept safely and appropriately at home. The National Audit Office’s cost-saving analysis shows that resolving more calls over the phone and discharging more patients at the scene in 2015-16 compared with 2011-12 avoided potential costs of around £74 million for ambulance services. However, non-conveyance may result in increased costs for other healthcare and social care services.

Citation and Funding

O’Cathain A, Knowles E, Bishop-Edwards L, et al. Understanding variation in ambulance service non-conveyance rates: a mixed methods study. Health Serv Deliv Res. 2018;6(19).

This project was funded by the National Institute for Health Research Health Services and Delivery Research Programme (project number 13/54/75).



NAO. NHS Ambulance services. London: National Audit Office; 2017.

NHS England. Ambulance quality indicators. London: NHS England; 2018.

NHS Wales. Ambulance quality indicators. Pontypridd: NHS Wales; 2018.

NHS England. Transforming urgent and emergency care services in England: Clinical models for ambulance services. London: NHS England; 2015.

NHS England. Transforming urgent and emergency care services in England: Safer, faster, better: good practice in delivering urgent and emergency care: A guide for local health and social care communities. London: NHS England; 2015.

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Where appropriate, patients can receive telephone advice only (“hear and treat”), or be discharged at the scene (“see and treat”), or taken to services such as urgent care centres, hospices and mental health units (“see and convey elsewhere”). Ambulance crews include advanced paramedics who can carry out diagnostic tests and basic procedures at the scene, administer drugs, and refer to other services. Telephone advice is given to patients by clinicians working in an ambulance service dispatch centre (clinical hub).  
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